Heat transferring means suitable for thermionic discharge apparatus



1946, A.' J Y OUNG 2,406,121 7 HEAT TRANSFERRING MEANS SUITABLE .THERMIONIC. DISCHARGE APPARATUS Filed- Jan 22,1943

Patented Aug. 20, 1946 h v 2,406,121

UNITED- STATES? PATENT orrlc HEAT TRANSFERRING MEANS SUITABLE FOR THERMIONIC DISCHARGE APPARATUS" Arthur J ames: Young, ,Danbury; England; ,assignor to-Radio Corporation oi America; a. corporation ofDelaware Application January'22, 1943', SerialNo: 473,172 8 Claims. (Cl. 25.0-27.5)

The present inventiomrelatesz'to:heattrans iftherearemore;than one barriersmnone-side ferring; apparatus wherein. it :is :required. to. efiect of all the barriers) isconstrained to pass betweem transference. otheat betweena stream: of fluid thefins in ordertoreach the othersideof'the and a metallicbody; barrler- (or barriers) and so to reach the outlet An objector the invention is toprovide 'a.:sim-= 5 at the other end'iof the duct.

ple-and eflicient cooling; IIIGaIISlfOT'aIL electron When-a single-barrier is us ed'itm'ay take the= discharge device. form of an=elliptica1= annulus extending from Though the invention is nottstrictly limited the top to thebottomdisc. With this form the j tothe transferenceof heat: from acylindrical fluid inlet passages at the successive discs w-ilL? anode of a tube to'a cooling. fluid. such as air; vary in size and in certain cases-this might-leach cross section.. The. invention is, however, to be considered. as applied to heat transferring ar- The coaxial cooling fins may consist. ofa humrangements: in which finsnareidisposedco-axially her ofmetaldiscs having acentral aperture in about and. inheat exchangingcontact. with the: which the metallic body, or anode of the tube; body and in which: the fins: are. mutually spaced fits tightlyso that it may be soldered" thereto apart. with'the minimum amount of solder. The discs Accordingtatheinvention; a heat transferringare'spacedapart by distance pieces ih theform device for effectingtransferenc'ezof'heatbetween of washers, which may be circular, fitting the a: stream of fluid: and a: metallic body, of the body-or anode.

kind" in which fins. areidisposed co axially about; In place of usinga series of discs to'form a and in heat exchanging contactwitlr the body, 2 built up unit the device may be made-by milling the fins I being mutually spaced apart, and in slotsin a -solid body'or'cylinderof brass orother" which the. body and' its fins-are accommodated suitable *good conducting metal.

in a duct of larger diameter (or of larger cross Theeapplicant'has, in connection with the-cool sectional area) than the outside diameter (or ing of the anodes of the thermionic devices; with cross sectional area) ofthe fins and" throughwhich he is principally concerned; commonly which duct the strea-miof fluid flows; ischarac-- used axial-air flow radiators with both coaxial terized in that there is provided between the*- and: radial cooling fins. For higli'specific load-" wall of the ductand' the' outer. edges of all of ings, the-coaxial coolingfins (i. e; those in-w-hich" the=fins at least one continuous barrier'whereby the stream of cooling fiuid moves radially inreach the other slde of the barrier (or barriers) radial length of radiator, and further the Inlet and so to reach the outlet at the other end of" 4 and outlet orifices of" the radiator itself cam the duct usually be of such dimensions that the speed" of According toa feature of the invention, acool-- flow: of thefiuid' will be suitableto the'case irr ing device for the (substantially cylindrical) which.. ax=sma1L radiator is required; Where the* anode of an electronic device, or vacuum tube,- primary requirement is small size then high iuct of larger diameter than'the outs1de d1a-m-- the latter case, axial flow with a radial fin 1s zter of the fins and through which cooling fluid 5 preferable. such as air) flowsis characterized in that there Di'fiicultieswith devices providing radial flow s-provided 'between the wall of the duct and the= (to which devices the present invention isdiruteredgesof. allthefinsatleastone continu-'-- rected) have been that'the addition of-suitabl'e |us barrier. whereby fluidenteringthe duct at means'for.admitting and'exhaustingth-e'air h'avw ne: end: thereof: on. one:.sidei .of the barrierrtor led. to large. increases in the diameter of} these 7 fluid is by way of at a temperature, at

'Many of the advanradial flow have there ballle) of 90 mm., and a diameter for the radiator of 80 mm. have been found suitable for an aircooled tube. The invention is illustrated in the accompanying drawing in which: 3

Fig. 1 is an elevational view, partly in section, showing cooling fins provided with a single barrier; and

V companying drawing,

' apoint-on the edge thence to the uppermost fin to join the upper- Fig. 2 is a fragmentary perspective view'of cooling fins provided with a double barrier.

at the two ends of a A particular embodiment of the invention,: in

to an air-cooled tube, is illusits application trated in .Fig. In thisembodiment the metallic anode A, which forms part of the envelope of the tube, is provided with tubular member AI, circular, washerlike radiator fins F, spaced apart from each other and in close heat exchanging relationship with the anode. Fitted about the edges of, all the washers is a continuous'barrier Bfwhich, as illustrated, consists of an elliptical annulus extending from the lower edge of the uppermost washer WI, past the edges of all the succeeding washers, to the upper edge (not visible in the figure) of the lowermost washer W2. The upper end of the annulus is in contact with the uppermost washer at oneend of a diameter of itand of the duct, and the lower end of the annulus is in' contact with the'lowermost washer at the Thus the duct is divided into two parts, between which the onlycommunication for, the cooling the spaces separating the several washers from each other. The assembly of tube and fins may be held, by means of a clamp, in a cylindrical fluid airduct K of larger internal diameter than the diameter of the washers, so that a space exists between the wall of the duct and the washers. The barrier is fitted between the wall of this duct and the edgesof the fins.

Suitably in such a heat transferring device eter of the fins is 80 m. m.,in which there are thirteen washers of brass 1.5 m. m. thick, having a root diameter of 42 m. m. and spaced apart 1.5 m. m., and in which the overall diameter of the duct is 90 m. m.,the dissipation of heat may be equivalent to 400 W for a current of air the inlet, of 30 C. flowing at the rate of 25 cubic feet/minute -(equivalent to a speed of approximately 1'7 metres/second), or to 800 W for a current of air at the same temperature flowing at the rate of 50 cubic feet/minute (equivalent to a speed of approximately 35 metres/second). The maximum temperature attained is 150 C.

If copper were used for the washers, the heat transferring device could be made smaller, but usually its not desired to make the noise'due to the higher speed of the air might be objectionable.

It will be appreciated that with a barrier as above described, the effective inlet and outlet orifices at the top and bottom of the device are widely different from each other. a modification illustrated by Figure 2 of the acl of the accompanymg drawing.

7 other end of the same diameter ,of the duct.

applied to such a tube, wherein the overall diamdiameter it smaller since By means of shape of the ,and through which duct the stream of fluid flows,

of on one side of in which two members B, or curved barriers are employed, a further improvement may be made by which these differences between the effective inlet and outlet orifices which in certain circumstances may be disadvantageous, may be reduced. In this arrangement, the two barriers maybe so constructed as, together, to constitute a continuous member bent so'asto extend from an edge of the uppermost fin at one end (1 of a diameter thereof to a point d" on the edge of the lowermostfin, back to the edge of the uppermost fin atthe opposite end of said diameter, down again to of the lowermost fin, and

most fin at the same one end (1 of the diameter, the two points d" on the lowermost fin being diameter thereof displaced from the first mentioned diameter. The barrier about the bends at d and d will determine whether there is any difierence between size of inlet and outlet. In thelimiting case, if the shape of the barrier at the bends were rectangular, the cross section could be made exactly equal, but in practice the corners might become almost dead. owing to ed-' dies, and therefore the most suitable shape would be found by experiment. 7

The barrier, or barriers, as the case maybe,

may be attached eitherto the inner wall of the; duct L, or to the outer edges of all or some of the washers.

7 Although, in the specific description, washers have been referred to, in which case the several washers would be separated by spacing or distance rings, or washers of smaller diameter than those constituting the fins; the radiator may be" produced from a solid cylinder of brass, or other suitable metal, in which have been cut. In either case, preferably be a close fit in the central orifice of the radiator so that it may be soldered to the inner wall of the orifice with a' minimum f solder and a minimum risk of having air pockets or gaps between the anode and radiator.

It is not necessary that the tube and its radiator be fixed in the duct L, it may merely be] slipped therein.

What I claim is:

l. A heat transferring device for effecting transference of heat between a stream of fluid and a cylindrical metallic body, of the kind in which a plurality of circular cooling fins are disposed coaxially about and in heat exchanging contact with the body, the fins being mutually spaced apart, nd in Which the body and its fins are accommodated in a cylindrical duct of larger and cross sectional area than the outside diameter and cross sectional area of the fins the anode should characterized in that there is provided between the wall of the duct and secured to different positions on the outer edges of all of the circui larcooling fins at least one continuous barrier whereby fluid entering the duct at one end therethe barrier is constrained to pass between the fins in order to reach the other side of said barrier and so toreach the outlet at the other end of said duct. 7

2. A cooling device for the anode of an elec-' tron discharge device in which circular cooling fins are disposed coaxially about and in heat exchanging contact with the anode, the circular, cooling fins being mutually spaced apart, and in which the anode and its cooling'fins are con circular co -axial slots centrically located in a cylindrical duct of larger diameter than the outside diameter of the fins and through which cooling fluid flows, characterized in that there is provided between the wall of the duct and the outer edges of all the fins at least one continuous barrier whereby fiuid entering the duct at one end thereof on one side of said barrier is constrained to pass between the fins in order to reach the other side of the barrier and so to reach an outlet at the other end of the duct.

3. A device as claimed in claim 1, wherein a single barrier is used which is in the form of an elliptical annulus extending from the topmost to the bottommost of said fins.

4. A device as claimed in claim 2 wherein a plurality of baflles are used so that equal inlet and outlet fluid passages can be obtained.

5. A heat transferring device for an air-cooled vacuum tube having an anode, said device having a plurality of coaxially spaced metallic fins surrounding said anode, comprising a fluid duct surrounding said fins, and two barriers which are so constructed as, together, to constitute a continuous member bent so as to extend from an edge of the uppermost fin at one end of a diameter thereof to a point on the edge of the lowermost fin, back to the edge of the uppermost fin at the opposite end of said diameter, down again to a point on the edge of the lowermost fin, and thence to the uppermost fin to join the uppermost fin at the said one end of the diameter, the two points on the lowermost fin being at the two ends of a diameter thereof displaced by from the first mentioned diameter.

6. A device as claimed in the preceding claim wherein the barriers are attached to the inner wall of the duct.

7. A cooling device for an electron discharge device having at least a cathode and an anode, comprising a plurality of mutually spaced circular metallic fins coaxially arranged to surround the anode of said electron discharge device, a cylindrical duct surrounding said circular fins and a continuous barrier surrounding and attached to a different position on each one of said fins, and so arranged as to divert the flow of a cooling fluid for said anode along different portions of said fins.

8. A cooling device for an electron discharge device having at least a cathode and an anode, comprising a plurality of mutually spaced circular metallic fins coaxially arranged to surround the anode of said electron discharge device, a cylindrical duct surrounding said circular fins and an elliptical barrier surrounding said fins and arranged to divert the flow of a cooling fluid along difierent portions of said fins.

ARTHUR JAMES YOUNG. 

